Regeneration of hair, namely, hair growth, is a topic of great interest for not only middle-aged and elderly people but also young people recently, and westernization of life style, including food, has been pointed out as a reason for hair loss among young people. Furthermore, interest in hair growth has become greater than ever from the viewpoint of improvement of the quality of life (QOL) which has been rapidly being of increased concern to middle-aged and elderly people with the aging of society. While the market for hair growth agents in Japan has been 30 billion yen as of 2005, this market size is unnaturally smaller than its potential size because the effect of commercially available hair growth agents has not been significant at present, but it is estimated that, if a reliable hair growth agent whose drug efficacy can be proven scientifically is developed, the market size for hair growth agents would be up to 200 billion yen in Japan, and even 2,000 billion yen worldwide (see “Research of Organ Regeneration Studies and their Feasible Medical and Economical Effect” (October 2006)). Thus, it is possible to say that at present society demands development of a reliable hair growth agent.
The fact that the effect of hair growth agents that are commercially available at present is not significant is due to the simple reason that the only evaluation methods at present utilize living animal and no proper evaluation system for evaluating a hair growth effect efficiently and globally is present. That is, because “a screening system for evaluating the effect of a hair growth agent globally and efficiently in vitro” is not present, a domestic market of potentially 200 billion yen has remained at 30 billion yen. Meanwhile, pharmaceutical companies commonly evaluated several tens of thousands to several millions of drugs at a high speed in conformity with their own procedures or joint development agreement by exploiting such a general drug development screening system, and as a result, drugs with excellent effects and safety have been developed. However, the development of hair growth agents has substantially deviated from the state of such common drug development. Minoxidil (Japanese name: Riup), which is currently the most reliable hair growth agent in the world, was originally developed as a therapeutic drug for a circulatory organ but has a history that its development was discontinued due to its severe side effects. However, a phenomenon of excessive hair growth was significantly found in an investigated subject in the course of a clinical investigation, and it was exploited as a hair growth agent but not as an original therapeutic drug for a circulatory organ. Although minoxidil was by chance found to be a hair growth agent with excellent results, nevertheless, a common understanding in the world is that the hair growth effect of minoxidil is not necessarily at a satisfactory level. Furthermore, a hair growth agent that was developed while focusing attention on the hair growth inhibiting function of an androgen has also been commercially available but its hair growth effect has not necessarily been highly appreciated. These facts mean that development of a hair growth agent has been conducted inefficiently, and if a process corresponding to that of usual drug development is possible, it would be possible to develop a more effective hair growth agent with excellent safety.
Meanwhile, it is thought that gray hair is caused by deterioration of the melanosome production function of a melanocyte for producing melanotic pigment (melanosome) due to its aging, or deterioration of the function of delivering melanosome produced by a melanocyte to a trichoblast for some reason(s), or deterioration of the melanosome-capturing function of a trichoblast. Regardless of the cause of gray hair, no method of recovery of original color of a gray hair has been present at all in the world at present. Whereas hair growth is principally of great importance for men, gray hair is of great importance not only for men but also for women.
Furthermore, reference will be made to fur as a material to make warm clothing in association with a hair growth technique. Conventionally, fur has a high utility value as a material to make warm clothing but its utilization has been challenged from the recent prevalence of the viewpoint of animal protection. However, no material of such high functionality to make warm clothing and replace fur presently exists. Therefore, if a technique for producing fur without killing an animal existed, it would be a start to resolving this problem.